Comments on: Disease-Spreading Zombies

By: chuckbukowski

chuckbukowski — Wed, 25 Jul 2012 08:16:52 +0000

Also, see this nice video http://www.youtube.com/watch?v=XuKjBIBBAL8

By: chuckbukowski

chuckbukowski — Wed, 25 Jul 2012 08:09:24 +0000

Very interesting topic, and nice examples! Another face of parasitism is that sometimes the parasite is very adapted to its host, and sometimes it’s the fact that humans are the wrong host that makes it deadly for us. Usually the problem is that while in the usual host the parasite tricks the immune system in a specific way, in humans it will make the immune system go crazy and cause anaphylactic attacks. This is the case of Echinococcus and I think of Telazia (a worm living in the eyes of dogs, transmitted to humans by a fly who drinks the tears of the dogs…. in humans it lives ok, but if it is disrupted in the attempt to take it out, the worm causes anaphylactic attacks).

By: John Baez

John Baez — Sat, 21 Jul 2012 09:27:14 +0000

That BBC story is interesting, thanks! They talk about how in decision-making we use dopamine signals to estimate the pleasure to be gained from our choices, and near the end they say:

Professor John Maule, an expert in decision making, at Leeds University Business School, said that in recent years people had begun to realise emotional or "gut instinct" decision making was just as important in human choices as analytical decision making.

Just in recent years? If so, it's about time! We are not disembodied 'rational agents' who primarily think by manipulating symbols according to rules; we're a complex stew in which chemical signals play a big role! People are just starting to learn how hormones like testosterone and cortisol affect decisions in the financial markets. A truly scientific approach to economics would ultimately need to take this kind of thing into account. Economists do talk about 'animal spirits', but I'm not sure how carefully they try to model them.

By: Nathan Urban

Nathan Urban — Fri, 20 Jul 2012 23:58:50 +0000

Carl Zimmer's book Parasite Rex may be of interest to readers of this blog post.

By: romain

romain — Fri, 20 Jul 2012 17:00:09 +0000

I had never heard about this before, that’s a great story! I very much liked the idea that T. Gondii may increase the dopamine production. Dopamine is ubiquitous in the brain and is much involved in decision-making. To my knowledge, most studies in neuroscience about the mechanisms of decision-making involve dopamine.
Here’s a short account by the BBC:

Dopamine levels in brain ‘influence decision making’

Also, a short comment: for a disease to spread, it seems like a very good idea to act differentially on genders. Even if the description of the change in behaviour in the article by Kathleen MacAuliffe is not quantified, it seems that it makes women more attractive (or more visible) and men much less. So that males will be more attracted to infected females who will then select only healthy males, therefore optimizing the infection rate.
If the effect was the same on both genders, either it would decrease the infection rate (if infected subjects are less visible) or increase the rate of infection of already infected subjects (if infected subjects are all more visible).

This somehow makes a link with evolutionary game theory!

By: daedalus2u

daedalus2u — Fri, 20 Jul 2012 14:58:46 +0000

This is interesting. I wonder if some of the neurodegenerative disorders are evolved compensatory responses to brain infections?

Maybe that is why the protein inclusions that are characteristic of neurodegenerative disorders are so toxic, it isn’t a bug, it is a feature.

Amyloid is a pretty good antibacterial agent.

http://www.ncbi.nlm.nih.gov/pubmed/20209079